Quenching of Fluorescence in Ionic Solutions

Abstract

The quenching of the fluoresence of 9-methyl-10-carboxy-ethyl anthracene in acid and alkaline conditions by KI is measured in aqueous solutions. No deviations from the Stern-Volmer equation are found for dilute solutions. Glycerol added to the solution alters the viscosity and the dielectric constant. With the uncharged molecule quenching is viscosity-controlled while with the negatively charged ion quenching is not limited by viscosity. In this case the dielectric constant is the important factor and iodide ions act as weak quenchers independent of viscosity.